Plaque accumulation in the walls of coronary arteries reduces the delivery of nutrients and oxygen to the myocardium. This luminal narrowing can cause clinical indications such as angina or heart attacks, and without treatment, can be fatal. One method of treatment is the percutaneous intervention of stents to re-canalize the vessel. A potential complication of stent implantation is arterial wall remodeling and renarrowing of the vessel; termed restenosis. This can be prevented in the majority of patients with an antiproliferative drug coating on the surface of the stent: a drug-eluting stent. I hypothesize that drug transport in the arterial wall from these devices varies between arterial locations (left anterior descending (LADC) versus right (RC) coronary artery; proximal, middle, versus distal regions). The purpose of this work was to identify the properties of the vascular wall that govern transport, and computationally model stent-based delivery to better understand any differences that could exist in transport based on location. The first aim of this work was to identify the porohyperelastic properties. Permeability showed a decrease along the length of the LADC artery of 198%, and 98.6% along the length of the RC artery (p=NS between LADC and RC). Mechanical properties indicated significant differences between the LADC and RC arteries, with the LADC artery being stiffer than the RC. The second aim of this work was to identify the mass transport and cellular binding properties. There was no difference between the LADC and RC arteries; however, diffusivity peaked in the middle region of both arteries by a factor of 2.07. Convection coupling coefficients indicated an upward trend down each artery with the RC artery having higher values. The third aim was to use the model constants from the previous two aims to create six parametric computational models of stent deployment and drug delivery into the respective arterial sections. Results indicated that RC sections had lower stress along with 2.2 times the species concentration at time points of peak smooth muscle cell migration and remodeling.

No description available.

No description available.

No description available.

Tissues are not solely composed of cells. The extracellular matrix is important for the cell well-being and cell-cell communication. The glycosaminoglycan hyaluronan (HYA) is a widely distributed extracellular matrix (ECM) component. The molecule has prominent physicochemical properties, foremost viscoelastic and osmotic, but participates in many biological processes such as cell migration, proliferation, tissue turnover, wound healing and angiogenesis. HYA is synthesised by either of three different hyaluronan-synthesising enzymes, HAS1-3, and its main ligand is the transmembrane receptor CD44. In the heart and vessels the matrix components are of great importance for endurance and elasticity which are prerequisites for a normal function. The aims of the study were to describe the distribution of HYA and its receptor CD44 in normal cardiovascular tissue and to investigate the ECM composition in myocardial hypertrophy. Normal conditions were studied in a rat model. These studies showed that the tunica adventitia in almost all vessels stained strongly for HYA. The expression in the tunica intima and media on the venous side, differed between the vessels and was almost absent on the arterial side. In the adult animals only minute amounts of CD44 were detected. The expression of both HYA and CD44 was increased in newborn rats. In the heart HYA was unevenly distributed in the interstitium. Strong HYA-staining was seen in the valves and in the adventitia of intramyocardial vessels. Almost no CD44-staining was observed. Notably, there was no obvious difference between newborn and adult animals. In an experimental rat model of pressure-induced cardiac hypertrophy the mRNA-levels of HAS1, HAS2, CD44, basic Fibroblast Growth Factor (FGF-2) and Fibroblast Growth Factor Receptor-1 (FGFR-1) were elevated on day 1 after aortic banding. HAS2, CD44 and FGFR-1 were at basal levels on day 42. The HYA-concentration was significally elevated on day 1. HYA was detected in the interstitium by histochemistry and CD44 was detected mainly in and around the intramyocardial vessels. The HYA-staining was increased in myectomi specimens from patients with HCM compared to controls. HYA was detected in the interstitium, in fibrous septas and in the adventitia of intramyocardial vessels. No CD44 was detected in HCM or in control specimens. Our results indicate that HYA and CD44 play an active role in the maturing vessel tree and that the ECM content of HYA is increased in experimental myocardial hypertrophy and human hypertrophic cardiomyopathy.

No description available.

Coronary arteries are the blood vessels supplying oxygen-rich blood to the heart muscles. Coronary artery calcium (CAC), which is the total amount of calcium deposited in these arteries, indicates the presence or the future risk of coronary artery diseases. Quantification of CAC is done by using computed tomography (CT) scan which uses attenuation of x-ray by different tissues in the body to generate three-dimensional images. Calcium can be easily spotted in the CT images because of its higher opacity to x-ray compared to that of the surrounding tissue. However, the arteries cannot be identified easily in the CT images. Therefore, a second scan is done after injecting a patient with an x-ray opaque dye known as contrast material which makes different chambers of the heart and the coronary arteries visible in the CT scan. This procedure is known as computed tomography angiography (CTA) and is performed to assess the morphology of the arteries in order to rule out any blockage in the arteries. The CT scan done without the use of contrast material (non-contrast-enhanced CT) can be eliminated if the calcium can be quantified accurately from the CTA images. However, identification of calcium in CTA images is difficult because of the proximity of the calcium and the contrast material and their overlapping intensity range. In this dissertation first we compare the calcium quantification by using a state-of-the-art non-contrast-enhanced CT scan method to conventional methods suggesting optimal quantification parameters. Then we develop methods to accurately quantify calcium from the CTA images. The methods include novel algorithms for extracting centerline of an artery, calculating the threshold of calcium adaptively based on the intensity of contrast along the artery, calculating the amount of calcium in mixed intensity range, and segmenting the artery and the outer wall. The accuracy of the calcium quantification from CTA by using our methods is higher than the non-contrast-enhanced CT thus potentially eliminating the need of the non-contrast-enhanced CT scan. The implications are that the total time required for the CT scan procedure, and the patient's exposure to x-ray radiation are reduced.

Pulmonary arterial thromboembolism (PATE) is the third most common acute cardiovascular disease after myocardial infarction and stroke. Frequently individual symptoms are nonspecific making clinical diagnosis of acute PATE difficult. Computed tomographic (CT) pulmonary angiography has become the first line examination performed in patients with suspected acute PATE. Severity of acute PATE directs treatment strategies and allows prognostication of outcomes. It is reported that patients with normal blood pressure and impaired RV function have a larger average PATE-related short-term mortality compared to patients with normal RV function. Cardiopulmonary CT with retrospective electrocardiographic synchronization allows simultaneous evaluation of pulmonary arterial bed, cardiac function, coronary arteries and thoracic aorta. We have used cardiopulmonary CT to detect right and left ventricular changes in the setting of acute PATE, to describe relationship between reduced right ventricular function and pulmonary arterial thromboembolic burden and to find best predictors of markedly reduced right ventricular ejection fraction. Reproducibility of right ventricular measurements in cardiopulmonary CT images and quality analysis of cardiopulmonary CT for evaluation of coronary arteries and thoracic aorta were done. Results of the study show that both the right and left ventricles develop detectable changes in acute PATE patients, the decrease of the right ventricular ejection fraction... [to full text] / Plaučių arterijos trombinė embolija (PATE) – sunki ūminė ir neretai atkrintanti širdies ir kraujagyslių liga. Tik miokardo infarktas ir galvos smegenų insultas yra dažnesni negu ūminė PATE. Ūminės PATE diagnostika nėra lengva. Klinikiniai simptomai dažnai esti neraiškūs ar nespecifiniai. Šiuolaikinėje klinikinėje praktikoje pirmo pasirinkimo tyrimas įtariant ūminę PATE yra plaučių arterijos kompiuterinės tomografijos (KT) angiografija. Sergančiųjų, kuriems dėl plaučių embolijos dar nėra išsivysčiusi sisteminė arterinė hipotenzija, mirštamumo rizika priklauso nuo embolijos apimties ir dešiniojo skilvelio būklės. Šie rodikliai rodo ligos sunkumą, kurį svarbu įvertinti parenkant ūminės PATE gydymą ir nusakant ligos prognozę. Taikydami sinchronizuotą su elektrokardiograma širdies ir plaučių KT norėjome aptikti dešiniojo ir kairiojo skilvelių būklės pokyčius sergantiesiems ūmine PATE, nustatyti sutrikusios dešiniojo skilvelio veiklos sąsajas su embolijos apimtimi bei aptikti rodiklius, tiksliausiai prognozuojančius ženklų dešiniojo skilvelio išstūmimo frakcijos sumažėjimą. Patikrinome, kaip tiksliai gali būti atkartojami dešiniojo skilvelio tūrio ir morfometrijos matavimai. Taip pat atlikome širdies ir plaučių KT vainikinių arterijų ir krūtininės aortos vaizdumo analizę. Nustatėme, kad įvykus ūminei PATE aptinkami ne tik dešiniojo bet ir kairiojo širdies skilvelio būklės pokyčiai, kad dešiniojo skilvelio išstūmimo frakcija mažėja proporcingai embolijos apimčiai, o dešiniojo ir... [toliau žr. visą tekstą]

In clinical anatomy, the renal venous system is relatively understudied compared to the arterial system. This investigation aims to clarify and update the variable patterns of the renal venous vasculature using cadaveric human (adult and foetal) and Chacma baboon (Papio ursinus) kidneys and to reflect on its clinical application, particularly in surgery and radiology. The study employed gross anatomical dissection and detailed morphometric and statistical analyses on resin cast and plastinated kidneys harvested from 211 adult, 20 foetal and 10 baboon cadavers. Radiological techniques were used to study intrarenal flow, renal veins and collateral pathways and renal vein valves. The gross anatomical description of the renal veins and its relations were confirmed and updated. Additional renal veins were observed much more frequently on the right side (31 %) than previously documented (15.4%). A practical classification system for the renal veins based on the number of primary tributaries, additional renal veins and anomalies is proposed. Detailed morphometric analyses of the various parameters of the renal veins corroborated and augmented previous anatomical studies. Contrary to standard anatomical textbooks, it was noted that the left renal vein is 2.5 times the length of its counterpart and that there are variable levels of entry of the renal veins into the IVC. Justification for the distal segment of the left renal vein to be termed the surgical trunk, and the proximal segment to be the homologue of the right renal vein is presented. Radiological investigations demonstrated a non-segmental and non-lobar intrarenal venous architecture, an absence of renal vein valves and extensive venous collaterals centering on the left renal vein. These collateral channels, present in the foetus, and persisting in the adult, may be operative and of clinical significance in pathological states. No sex differences and no race differences of note were recorded in this study. The Chacma baboon displayed similar intra-renal venous anatomy. The applied clinical anatomy of these findings with particular regard to renal surgery and uro-radiology is emphasised. / Thesis (M.D.)-University of Natal, 1993.

Magnetic resonance imaging is often used as a source for reconstructing vascular anatomy for the purpose of computational fluid dynamics (CFD) analysis. We recently observed large discrepancies in such “image-based” CFD models of the normal common carotid artery (CCA) derived from contrast enhanced MR angiography (CEMRA). A novel quantitative comparison of velocity profile shape of N=20 cases revealed an average 25% overestimation of velocities by CFD, attributed to a corresponding underestimation of lumen area in the CEMRA-derived geometries. We hypothesized that this was due to blurring of edges in the images caused by dilution of contrast agent during the relatively long elliptic centric CEMRA acquisitions, and confirmed this with MRI simulations. CFD simulations incorporating realistic inlet velocity profiles and non-Newtonian rheology had a negligible effect on velocity profile skewing, suggesting a role for other sources of error or modeling assumptions.